Use of water-external micellar dispersions in oil recovery



United States Patent 3,506,071 USE OF WATER-EXTERNAL MICELLAR DISPERSIONS IN OIL RECOVERY Stanley C. Jones, Littleton, Colo., assignor to Marathon Oil Corporation, Findlay, Ohio, a corporation of Ohio No Drawing. Filed Dec. 26, 1967, Ser. No. 693,125

Int. Cl. E21b 43/16 U.S. Cl. 166-273 23 Claims ABSTRACT OF THE DISCLOSURE Secondary-type crude oil recovery is effected by injecting into a subterranean formation 120% formation pore volume of a water-external micellar dispersion of hydrocarbon and petroleum sulfonate dispersed in water and moving it through the formation to displace crude oil therefrom.

BACKGROUND OF THE INVENTION United States Patent No. 3,266,570 to Gogarty teaches a flooding process using an oil-external solu ble oil followed by a water-external emulsion. Gogarty teaches that .the back portion of the water-external emulsion improves the miscibility with a subsequent water drive.

United States Patents No. 3,330,344 and 3,348,611 to Reisberg teach flooding with an aqueous solution containing swollen miscelles of a surfactant and an amphiphilic polar organic compound. Reisberg teaches that these solutions will solubilize the crude oil in sand packs. Suitable amphiphilic organic compounds include higher molecular weight monohydroxy aliphatic and alicyclic alcohols containing six or more carbon atoms.

Applicants have discovered that a water-external micellar dispersion comprised of water, hydrocarbon and petroleum sulfonate is useful in secondary-type recovery processes (especially tertiary recovery) to recover crude oil from subterranean formations. Preferably, the micellar dispersion contains semi-polar compound and optionally electrolyte. The injection of about 1 to about 20% formation pore volume of the micellar dispersion provides eificient recovery of crude oil from a subterranean formation. The micellar dispersion can be followed by a mobility buffer, one purpose of which is to protect the dispersion from invasion of a subsequent water drive.

DESCRIPTION OF THE INVENTION This invention is applicable to crude oil recovery processes where artificial means facilitate removal of the oil. More specifically, the invention is applicable to secondary oil recovery and to tertiary recovery processes in subterranean formations which have been reduced to residual oil saturation.

The term micellar dispersion as used herein is meant to include micellar solutions, water-external micro-emulsion [Schulman and Montague, Annals of the New York Academy of Sciences, 92, pages 366371 (1961)], transparent emulsions, and micellar dispersion technology taught by C. G. Sumner, Claytons, The Theory of Emulsions and Their Technical Treatment, 5th edition, pp. 315-320 (1954). Micellar dispersions differ from emulsions in many ways, the strongest differentiation being that the former are thermodynamically stable whereas the latter are not.

The micellar dispersions of this invention are waterexternal. That is the hydrocarbon phase is internally dispersed. In an oil-external micellar dispersion the water phase is internally dispersed.

The micellar dispersion is composed essentially of hydrocarbon, an aqueous medium, petroleum sulfonate sufficient to impart thermodynamic stability to the solution,

3,506,071 Patented Apr. 14, 1970 semi-polar organic compound and optionally electrolyte. Examples of volume amounts are from 1% to about 50% of hydrocarbon, from about 40% to about aqueous medium, at least about 4% sulfonate, from about 0.01% to about 5% of semi-polar compound and up to about 4% by weight of electrolyte. In addition, the dispersions and/or subsequent slugs can contain corrosion inhibiting agents, bactericides, etc.

Examples of hydrocarbon include crude oil (both sweet and sour) and partially refined fractions thereof, e.g., side cuts from crude columns, crude column overheads, gas oils, kerosene, heavy naphthas, naphthas, straightrun gasoline, and liquefied petroleum gases. Pure hydrocarbons are also useful, e.g. parfi'in compounds including propane, pentane, heptane, decane, dodecane, etc.; cycloparafiins compounds including cyclohexane, etc.; aryl compounds including benzene, naphthalene, anthracene, etc.; alkylated products thereof including toluene, alkyl phenols, etc. Based on economics, the preferred hydrocarbon is one locally available and is crude oil. The unsulfonated hydrocarbon (e.g. heavy vacuum gas oils) in petroleum sulfonates is also useful.

The aqueous medium can be soft, brackish, or a brine. Preferably, the water is soft but it can contain small amounts of salts which are compatible with the ions in the subterranean formations being flooded.

Petroleum sulfonates (i.e. surfactants) useful with the micellar dispersion are also known as alkyl aryl naph thenic sulfonates. Such can be obtained by sulfonating at least a portion of a sulfonata ble hydrocarbon (e.g. gas oils) and then neutralizing the mixture, e.g. with NH OH, NaOH, etc. Examples of sulfonates include those containing 60-100% active sulfonate. Unsulfonated hydrocarbon within the sulfonates is useful as the hydrocarbon within this invention. Examples of preferred surfactants are the sodium and ammonium petroleum sulfonates having an average molecular weight of from about 360 to about 520, and more preferably from about 420 to about 470. The sulfonate can be a mixture of low and high molecular weight sulfonates.

The semi-polar organic compound (also known as cosurfactants and co-solubilizers) useful with the invention can have limited water solubility. However, compounds having 0 to infinite water solubility are useful. Preferably, they have limited water solubility of from about 0.01% to about 20% and more preferably from about 1% to about 5% at ambient temperature. Examples of semi-polar compounds include alcohols, amino compounds, esters, aldehydes and ketones containing from 1 up to about 20 or more carbon atoms and more preferably from 3 to about 16 carbon atoms. The semi-polar compound is preferably an alcohol, e.g. isopropanol, nand isobutanol, the amyl alcohols such as n-amyl alcohol, 1- and Z-hexanol, 1- and 2-octanol, decyl alcohols, alkaryl alcohols such as p-nonyl phenol and alcoholic liquors such as fuel oil. Particularly useful alcohols include the primary butanols, primary pentanols and secondary hexanols. Concentrations of from about 0.01% to more than about 5 volume percent of the semi-polar compound is useful in the micellar dispersion and more preferably from about 0.2 to about 3%. Mixtures of two or more semi-polar compounds are useful in the micellar dispersions.

Electrolytes are useful within the water-external micellar dispersions. Examples of such electrolytes include inorganic bases, inorganic acids, inorganic salts, organic bases, organic acids, and organic salts which are strongly or weakly ionized. Preferably, the electrolytes are inorganic bases, inorganic acids and inorganic salts, e.g. sodium hydroxide, sodium chloride, sodium sulfate, hydrochloric acid, sulfuric acid, sodium nitrate, ammonium chloride, ammonium hydroxide, and potassium chloride.

Examples of other useful electrolytes can be found in United States Patent No. 3,330,343. The type and concentration of electrolyte will depend on the aqueous medium, sulfonate, semi-polar organic compound, hydrocarbon and on the reservoir temperature. The use of acids or neutral salts is preferred with dispersions containing hydrophilic sulfonates and high reservoir temperatures. Electrolytes yielding a higher pH, e.g. NaOH are preferred with more oleophilic sulfonates.

The mobility of the micellar dispersion should be about equal to or less than the mobility of the fluids ahead of it, i.e. the combination of the crude oil and formation water within the subterranean formation. Such a mobility is desired to avoid viscous fingering of the micellar dispersion into the formation fluids.

The volume of the micellar dispersion useful with this invention is from about 1% to about 20% formation pore volume. Larger percentage pore volumes are useful but may be economically unattractive. More preferably, from about 2% to about 10% formation pore volume is useful and 3% to about 6% formation pore volume gives very efficient results. The micellar dispersion is injected through an injection means into the formation. The injection means includes the well bore including that area contiguous to the oil-bearing rock at the bottom of the well.

The size of the mobility buffer (also identified as the front portion of the drive material) can vary from about to about 75% formation pore volume and more preferably is within the range of from about 25% to about 60% formation pore volume. However, this formation pore volume can be adjusted to satisfy the require- 4 EXAMPLE 1 Fired Berea sandstone cores 4 feet long by 3 inches in diameter having characteristics indicated in Table I are saturated with distilled water containing 18,000 p.p.m. of NaCl, flooded to irreducible Water saturation with a crude oil obtained from the Henry lease in Illinois (hereinafter identified as Henry produced crude and having a viscosity of 5.9 cp. at 72 F. and a specific gravity of 0.833) and are then flooded to residual oil saturation with water obtained from the Henry lease in Illinois (hereinafter identified as Henry plant water, example of an analysis is 17,210 p.p.m. of total dissolved solids and having a pH of 7.7). The cores are then flooded with the indicated percent pore volumes of a water-external micellar dispersion containing 80.5% of water obtained from the Palestine water reservoir in Palestine, Ill. (hereinafter identified as Palestine water, example of an analysis is 412 p.p.m. of total dissolved solids and having a pH of 7.6- 8.0), 8.7% of an ammonium alkyl aryl naphthenic sulfonate (having an average molecular weight of about 440 and containing 78.3% active sulfonate and the residue unsulfonated paraffinic oil), 1.1% of n-amyl alcohol, 0.5% isopropanol, and 9.2% of Henry produced crude. After the micellar dispersion is injected into the cores, there is injected 1.2 pore volumes of thickened water solution (mobility buffer) composed of Palestine water, 1,200- p.p.-m. of No. 530 Pusher (a high molecular weight partially hydrolyzed polyacrylamide sold by Dow Chemical Company) and 1% fusel oil. The core characteristics, percent pore volume of micellar dispersion slugs and the results of the flooding tests are indicated in Table I.

TABLE I Percent formation pore Core characteristics volume of Effective (percent) micellar dispersion injected into core Percent recovery of crude oil in core Residual oil saturation (percent) porosity Permeability The fluid recovered from Sample C was analyzed and found to contain 32.8% of the ammonium petroleum sulfonate originally incorporated into the micellar dispersion.

ments of the particular reservoir being flooded. The mobility buffer can have a mobility about equal to or less than the mobility of the micellar dispersion. In addition, from about 5% to about 100% of the mobility bufler can be characterized as having graded mobilities from a low at the front portion of the mobility buffer to a high at the juncture with a subsequent water drive.

After the mobility buffer is injected into the subterrean formation, suflicient water drive is injected to move or dis- EXAMPLE 2 The procedure of Example 1 is repeated except the micellar dispersion is composed of 71% Palestine water, 1.3% n-amyl alcohol, 0.5% isopropanol, 9.9% of ammonium petroleum sulfonate, and 17.3% of Henry produced crude. The core characteristics, percent pore volumes, and percent crude oil recovery results are indicated in Table II:

TABLE II Percent pore Core charactesistics volume of micellar Percent Efiective Residual oil dispersion recovery of porosity Permeability saturation injected into crude oil in Sample (percent) (m.d.) (percent) core core place the water-external micellar dispersion and mobility EXAMPLE 3 buffer toward production means, egg. production well, in fluid communication with the subterranean reservoir. Crude oil displaced by these injected fluids is recovered through the production well.

The following examples are presented to specifically illustrate working embodiments of the invention. Limitations are not to be implied by these examples. It is intended that all equivalents obvious to those skilled in the art be included within the scope of the invention. Per- Fired Berea sandstone cores 4 feet long by 2 inches in diameter, having characteristics indicated in Table III, are saturated with Henry plant water, flooded to irreducible water saturation with Henry produced crude, and then waterflooded to residual oil saturation with Henry plant water. The cores are then injected with waterexternal micellar dispersions composed of 27.41% Henry produced crude, 6.67% of an ammonium petroleum sulfonate, having an average molecular weight of about 450 cents are based on volume, unless otherwise specified. and composed of about active sulfonate, 64.62% of s, A r

Palestine water containing 0.98 weight percent of sodium hydroxide, 0.74% of isopropanol, and 0.56 of nonylphenol. The micellar dispersion has a viscosity of 29.5 cp. at 72 F. The micellar dispersion injections are followed with 1.25 pore volumes of a thickened water slug composed of 800 p.p.m. of No. 530 Pusher, 4% of isopropanol, 50 p.p.m. of NH SCN, and 96% of Palestine water.

To show that the water-external systems have comparable recoveries to that of oil-external micellar systems, the above procedure is repeated except the core is flooded with 3% pore volume of an oil-external micellar dispersion composed of 59.35% of crude column overheads (a heavy naphtha), 7.79% of ammonium petroleum sulfonate, 31.35% of Palestine water containing 0.94 weight percent of sodium hydroxide, 1.36% of isopropanol, and 0.15% of nonyl-phenol. This micellar dispersion has a viscosity of 33.2 cp. at 72 F.

The results of the flooding tests are indicated in Table III:

6 Samples G-H 27.42% of Henry crude oil,

6.67% of the above ammonium petroleum sulfonate,

0.74% of isopropanol,

0.56% of nonyl phenol,

64.61% of Palestine water containing 0.979 Weight percent of sodium hydroxide.

After the dispersions are injected into the core samples, 1.2 pore volumes of thickened water slugs are injected into the cores, compositions of the thickened water slugs being:

Eample B 0 800 p.p.m. of No. 530 Pusher,

50 p.p.m. of NH SCN, 0.08% of isopropanol, and 99.9% of Palestine water.

TABLE III Percent Core characteristics formation pore volume Percent Efiective Pemiea Residual oil of micellar recovery of por sity bility saturation dispersion crude oil in Sample percent) (m.d.) (percent) injected core Water-external systems:

A 19. 7 234 35. 9 3 80.1 B 19. 3 222 35. 2 5 87. 3 Oil-external system: C 20.0 297 36. 7 3 83.1

EXAMPLE 4 Samples A and C-H Fired Berea sandstone cores 4 feet long by 2 inches in diameter having characteristics indicated in Table IV are treated as follows: (1) Samples C, D, and F are first saturated with distilled water containing 16,500 p.p.m. of NaCl, flooded to irreducible water saturation by using Henry crude oil and flooded to residual oil saturation 800 p.p.m. of No. 530 Pusher, p.p.m. of NH SCN,

4% of isopropanol, and

96% Palestine Water.

The results of the flooding tests are indicated in Table IV:

TABLE IV Core characteristics Percent pore volume Percent Percent Efiective Residual oil injection recovery of recovery of porosity Permeabilsaturation of dispercrude oil sulfonate Sample (percent) ity (m.d.) (percent) sion slug in core injected with distilled water containing 16,500 p.p.m. of NaCl, (2) EXAMPLE 5 Samples A, B, E, and G-H are treated as above except they are waterflooded with Henry plant water. Thereafter, the cores are injected with Table IV indicated percent formation pore volumes of water-external micellar dispersions composed of:

Samples A-B Samples C-F 26.85% Henry crude oil,

6.47% of the above ammonium petroleum sulfonate,

3.21% of isopronpanol,

0.81% of nonyl phenol,

62.66% of Palestine water containing 0.979 weight percent of sodium hydroxide.

Fired Berea sandstone cores 4 feet long by 2 inches in diameter having characteristics indicated in Table V are saturated with distilled water containing 18,000 p.p.m. of NaCl, flooded with Henry crude oil to irreducible water saturation and then flooded with Henry plant water to residual oil saturation. The cores are then flooded at ambient temperature with indicated percent formation pore volumes of a micellar dispersion having the compositions indicated in Table V:

TABLE V Micellar dispersion composition (percent) Component Aqueous medium:

(1) Henry plant water 34. 8 89. 75 93. 15 (2) Palestine water 52. 2 Su1lonateA1mnonium petroleum sulionate having:

(a) Average MW=440, 78.3% active sultonate 8. 24 (b) Average MW=450, 78.8% active sulfon e 5. 69 (0) Average MW=440, 87.6% active sul n e 9. 55 Semi-polar organic compound:

(1) n-Amyl alcohol 3. 38 1. 57 0. 35 (2) n-Butyl alcohol. 0. 19 (3) Isopropanol. O. 07 0. 44 0. 62 Viscosity at 72 F 47. 4 16. 0 l7. 0

7 8 The core samples are then flooded with 1.2 formation jection means in fluid communication with at least one pore volume of a thickened water solution having the production means, comprising: following compositions: (1) injecting through the injection means into the fors 1 mation 1% to about 20% formation pore volume amp e of a water-external micellar dispersion comprlsed Palestine Water containing 1% fusel oil and 1200 of hydrocarbon dispersed in an aqueous medium, and ppm. of No. 530 Pusher. petroleum sulfonate and semi-polar organic compound, then Samples and cal (2) injecting a mobility buffer into the formation, the Palestine water containing 1% of n-butanol and 1200 bilit b ff h t i ed as having a mobility ppm. f N0. 530 Pushcrabout equal to or less than that of the formation Results of the flooding tests are indicated in Table VI: fluid within the subterranean formation, and

TABLE VI Core characteristics Micellar dispersion Percent for- Percent remation pore covery of Effective Permea- Percent v l m in de oil porosity bility residual oil jeeted into in Sample (percent) (1nd.) saruration Type core core 20.2 430 37.9 A 2.5 87.2 21. 1 535 28. 4 B 5. 0 77. 3 17. 4 123 37. 5 B 5. 0 2. 4 21. s 481 31. 4 c 5. 0 74. 2

What is claimed is: (3) injecting sufiicient water drive into the formation 1. A process for recovering crude oil from an oilto move the micellar dispersion and mobility buffer bearing subterranean formation having at least one in toward a production means and recovering crude jection means in fluid communication with a least one oil therefrom. production means, comprising injecting through the in- 14. The process of claim 13 wherein the micellar jection means into the formation a water-external miceldispersion contains electrolyte. lar dispersion comprised of hydrocarbon, an aqueous me- 15. The process of claim 13 wherein the mice lar dium and petroleum sulfonate and displacing the micellar dispersion has a mobility about equal to or less than dispersion toward the production means to recover crude that of the formation fluids ahead of the dispersion. oil therefrom. 16. The process of claim 13 wherein the mobility 2. The process of claim 1 wherein the water-external buffer is characterized has having an average mobi ity micellar dispersion contains semi-polar organic combetween that of the micellar dispersion and that of the pound. water drive.

3. The process of claim 1 wherein the Water-external 17. The process of claim 13 wherein from about 2% micellar dispersion contains electrolyte. up to about 10% formation pore volume of micellar 4. The process of claim 1 wherein the micellar disperdispersion is injected into the subterranean formation. sion contains at least about 4% by volume of the sul- 18. The process of claim 13 wherein from about 5% fonate. to about 75% formation pore volume of mobility buffer '5. The process of claim 1 wherein the petroleum sulis injected into the formation. fonate has an average molecular weight of from about 19. The process of claim 13 wherein from about 5% 360 to about 520. to about 100% of the mobility buffer is characterized as 6. The process of claim 1 wherein the petroleum sulhaving graded mobilities increasing from front to rear. fonate is a sodium or ammonium sulfonate having an 20. The process of claim 13 wherein the petroleum average molecular weight of from about 420 to about Sulfonate within the micellar dispersion has an average 470. molecular weight of from about 420 and about 470.

7. The process of claim 1 wherein the hydrocarbon is 21. The process of claim 13 wherein the micellar disunsulfonated hydrocarbon in the petroleum sulfonate. persion contains at least about 4% by volume of the 8. The process of claim 1 wherein from about 1% to sulfonate. about 20% formation pore volume of the micellar dis 22. The process of claim 13 wherein the petroleum persion is injected into the formation. sulfonate is sodium sulfonate or ammonium sulfonate.

9. The process of claim 1 wherein the mobility of the 23. The process of claim 13 wherein the hydrocarbon micellar dispersion is about equal to or less than the is unsulfonated hydrocarbon in the petroleum sulfonate. mobility of the formation fluids ahead of the micellar dispersion within the subterranean formation. f ren s Cited 10 The process of claim .1 wherein a mobility buffer UNITED STATES PATENTS 1s ln ected mm the format1on after the micellar dlspersion is injected therein. 3,261,399 9 6 Coppel 1669 11. The process of claim 10 wherein the mobility 3,266,570 9 6 Go garty 166-9 buffer has a mobility about equal to or less than that of 3,330,344 7 Rcisberg 166-9 the micellar dispersion. 3,348,611 10/1967 Relsberg 166-9 12. The process of claim 11 wherein from about 5% 3,373,809 3/ 1968 C oke 166--9 up to about 100% of the mobility buffer is characterized as having graded mobilities increasing from front to STEPHEN J. NOVOSAD, Primary Examiner rear.

13. A' process of recovering crude oil from an oil- US. Cl. XLR. bearing subterranean formation having at least one in- 1 66-274 Patent No.

Inventor(s) UNITED STATES PATENT OFFICE It is certified that error appears in the above-identified patent Column 1, line 28:

Column 2, line 14:

Column 2, line 57:

Column 5, Table III: In the heading:

Column 5, line 72:

Column 6, line 13:

Table IV: Sample B Under Effective Porosity Table VI, heading:

Table VI, under Effective Porosity B-2 C-1 Under Percent recovery of Crude Oil B- 2 Under Table VI:

and that said Letters Patent are hereby corrected as shown below:

Delete 'miscelles" and insert --micelles--.

Delete 'parffin" and insert ---paraffin--,

Delete "fuel" and insert --fusel--.

Delete 'Effective por sity percent)" and insert --Effective porosity (percent)--.

Delete "isopronpanol, and insert --isopropanol--,

Delete "Eample" and insert --Sample--.

Delete "18. 2'! and insert ---18. 6--.

Delete 'Percent residual oil saruration' and insert --P ercent residual oil saturatio Insert the following footnote:

(see page 2) mgr UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3, 506, 071 D d April 14, 1970 Inventor(s) Stanley Jones It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

-- This example shows that the hydrocarbon in the sulfonate (i. e. the sulfonate contains the indicated active sulfonate and the residue is unsulfonated hydrocarbon) will suffice in the micellar dispersions of this invention.

Column 8, line 34: Delete "has" and insert --as--.

Column 8, line 48: Delete 'emd" and insert ---to--.

SIGNED AZZU SL'ILFID Auezsm (SEAL) I E. JR. Edward M. Fiddl r. J flomissioner of Patents Atteating Officer 

